39 CFR § 762.11 - General.
The Postal Service, at its discretion, issues a specialized postal money order, designated a Disbursement Postal Money Order in payment of Postal Service obligations. Disbursement Postal Money Orders are distinguishable on their face from other postal money orders in the following ways:
(a)Disbursement Postal Money Orders have words of negotiability - “Pay to the order of” - printed on their face, while other postal money orders simply bear the words “Pay to” on their face;
(b) Disbursement Postal Money Orders, unlike other postal money orders, bear on their face the phrase, “This special money order is drawn by the Postal Service to pay one of its own obligations.”; and
(c) The amounts of Disbursement Postal Money Orders are printed in words as well as numbers, while the amounts of postal money orders available at post offices are printed in numbers only.